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Math 430: Theory of Numbers

I am your instructor Prof Geske (guess-key) and am happy to welcome you to the course! Please explore the course webpage.

Announcements

Welcome!

Welcome! This is your Math 430 instructor Prof Geske! I would like you to kindly do the following prior to your first lecture.

  • Access the ☞ course webpage and read through it. Almost all of the course content, including the syllabus, is found at this webpage. I will not discuss the syllabus in great detail during lecture, but will be happy to answer questions about it, so do read through it first.
  • Verify that you do not have any conflicts with the assigned exam dates. Email me immediately if you do!
  • Only if you require testing accomodations: initiate your registration with ☞ OSAS.
  • Access the Lecture 1 handout in the ☞ Daily Schedule on the course webpage. I will print a copy for you for the first lecture, however you may also prepare it on your own notetaking device.
  • Access ☞ Brightspace and find our course page.
    • Click the Gradescope tab and sign up.
    • Click the Poll Everywhere tab and sign up.
  • You should also have received an announcement on Brightspace detailing the Course ID and Course Key for our ☞ MyOpenMath course. Please sign up.

sent: Fri Aug 21

Old Announcements

Office Hours

Instructor Email Office Hours Location
Prof Geske geske (at) usc (dot) edu KAP 244A
Yijie Pan yijiepan@usc.edu Math Center (KAP 263)

You are encouraged to attend the office hours of any instructor. To gain the greatest advantage from office hours I recommend preparing your questions in advance. If it is impossible for you to attend these office hours but would still like to meet: feel free to reach out to your instructor or TA to schedule an alternative time to meet.

Time Start Time End Mon Tue Wed Thu Fri
9AM 10AM
10AM 11AM
11AM 12PM
12PM 1PM
1PM 2PM
2PM 3PM
3PM 4PM
4PM 5PM Geske
5PM 6PM Geske
6PM 7PM Geske

Daily Schedule

In this table you will find a pdf scaffold posted before each lecture, which we will fill in during class. Below each scaffold you will find a corresponding list of problems from the ☞MyOpenMath practice. You will also find posted, after each exam, solutions to that exam.

Monday Tuesday Wednesday Thursday Friday
Aug 24

Lecture 01 (A1)
A1: Q1-Q4
Aug 25 Aug 26

Lecture 02 (A1)
A1: Q5-Q9
Aug 27

Groupwork 1
Aug 28

Lecture 03 (A1A2)
Aug 31

Lecture 04 (A2)
Sep 01 Sep 02

Lecture 05 (A2)
Sep 03

Groupwork 2
Sep 04

Lecture 06 (A2A3)
Sep 07

No Class
Sep 08 Sep 09

Lecture 07 (A3)
Sep 10

Groupwork 3
Sep 11

Lecture 08 (A3A4)
Sep 14

Lecture 09 (A4)
Sep 15 Sep 16

Lecture 10 (A4A5)
Sep 17

Groupwork 4
Sep 18

Lecture 11 (A5)
Sep 21

Lecture 12 (A5B1)
Sep 22 Sep 23

Lecture 13 (B1)
Sep 24

Groupwork 5
Sep 25

Lecture 14 (B1)
Sep 28

Midterm A
Sep 29 Sep 30

Lecture 15 (B2)
Oct 01

Groupwork 6
Oct 02

Lecture 16 (B2)
Oct 05

Lecture 17 (B3)
Oct 06 Oct 07

Lecture 18 (B3)
Oct 08

No Class
Oct 09

No Class
Oct 12

Retake A
Oct 13 Oct 14

Lecture 19 (B4)
Oct 15

Groupwork 7
Oct 16

Lecture 20 (B4)
Oct 19

Lecture 21 (B5)
Oct 20 Oct 21

Lecture 22 (B5)
Oct 22

Groupwork 8
Oct 23

Lecture 23 (C1)
Oct 26

Midterm B
Oct 27 Oct 28

Lecture 24 (C1)
Oct 29

Groupwork 9
Oct 30

Lecture 25 (C2)
Nov 02

Lecture 26 (C2)
Nov 03 Nov 04

Lecture 27 (C3)
Nov 05

Groupwork 10
Nov 06

Lecture 28 (C3)
Nov 09

Retake AB
Nov 10 Nov 11

No Class
Nov 12

Groupwork 11
Nov 13

Lecture 29 (C4)
Nov 16

Lecture 30 (C4)
Nov 17 Nov 18

Lecture 31 (C5)
Nov 19

Groupwork 12
Nov 20

Lecture 32 (C5)
Nov 23

Midterm C
Nov 24 Nov 25

No Class
Nov 26

No Class
Nov 27

No Class
Nov 30

Lecture 33 (finalonly)
Dec 01 Dec 02

Lecture 34 (finalonly)
Dec 03

Groupwork 13
Dec 04

Retake ABC
Dec 07

No Class
Dec 08

No Class
Dec 09

Final Exam

Syllabus

The content of this syllabus is subject to change.

Section Time Location
39651 MWF 2-2:50pm KAP 163

Course Materials

The textbook is recommended but not required.

Textbook Author Edition
Elementary Number Theory Burton 6th

Course Structure

This course is broken up into Unit A, Unit B, and Unit C. Each unit consists of 5 topics. For a total of 15 topics. There is also a topic that is exclusive to the final.

Topic Name Description
A1 Induction and Binomial Theorem Use the principles of mathematical induction. Use the binomial theorem. Use properties of binomial coefficients.
A2 Divisibility, Gcds, and Lcms Use the division algorithm. Use properties of divisibility and gcds and lcms.
A3 Euclidean Algorithm and Diohpantine Equations Use the Euclidean algorithm to find gcds. Solve diophantine equations.
A4 Primes and Fundamental Theorem of Arithmetic Use the fundamental theorem of arithmetic. Prove variations of the fundamental theorem. Use the Sieve of Eratosthenes.
A5 Sequences of Primes Prove results related to infinitudes of primes in sequences of particular types.
B1 Modular Arithmetic Calculate residues and assess divisibility using modular arithmetic.
B2 Linear Congruences and Chinese Remainder Theorem Solve linear congruences. Use the Chinese remainder theorem. Prove results relating to the two.
B3 Fermat's Little Theorem Use Fermat's Little Theorem. Prove related results. Identify pseudoprimes.
B4 Wilson's Theorem Use Wilson's Theorem and its corollary on square roots of negative one. Prove related results.
B5 Number Theoretic Functions Use and prove results related to the tau and sigma functions. Prove results about number theoretic functions.
C1 Mobius Inversion and Convolutions Use and prove results related to convolutions and the Mobius inversion formula.
C2 Floor Function And Change of Base Use and prove results related to the floor function. Calculate powers of primes dividing factorials. Do this working relative other bases.
C3 Euler Phi Function Use and prove results relating to the Euler Phi function.
C4 Euler's Theorem Use Euler's theorem and prove related results. Relate phi to convolutions.
C5 Order and Primitive Roots Prove results related to the order of an integer and primitive roots.
Final Only Quadratic Reciprocity and Cryptography Solve and prove results related to quadratic congruences. Use Euler's criterion and Legendre symbols to consider quadratic residues. Prove results related to quadratic reciprocity. Interpret cryptographic schemes using number theory.

See the ☞ Daily Schedule for a day-by-day breakdown of our progression through the units.

Grading is broken up into Topic Mastery, PollEverywhere, Discussion Group Work, and the Final Exam.

Category Weight Total Quantity of Items in Category Weight Per Item
Topic Mastery 60% 15 topics 4% per topic
Discussion: Groupwork 10% [13 groupworks - lowest 2 dropped] = [11 counted groupworks] ~0.91% per counted groupwork
Lecture: PollEverywhere 5% [~2 polls per lecture - lowest 10 droppped] = [~60 counted polls] ~0.08% per counted poll
Final Exam 25% 1 exam 25%
Topic Mastery

There are 15 topics (A1-A5, B1-B5, C1-C5) which were listed earlier in the syllabus.

Individual Topic Grading. Each topic is graded out of 4 points. 4 points indicates mastery. Topic grading will be assessed using Midterms and Retakes.

Date Assessment Time Location
Mon 9/28/26 Midterm A Your Lecture Time Your Lecture Classroom
Mon 10/12/26 Retake ≤A Your Lecture Time Your Lecture Classroom
Mon 10/26/26 Midterm B Your Lecture Time Your Lecture Classroom
Mon 11/9/26 Retake ≤B Your Lecture Time Your Lecture Classroom
Mon 11/23/26 Midterm C Your Lecture Time Your Lecture Classroom
Fri 12/4/26 Retake ≤C Your Lecture Time Your Lecture Classroom

Each Midterm is tied to a unit and will have a single problem (with parts) for each each topic in that unit. For example Midterm A is tied to Unit A and will have A1, A2, A3, A4, and A5 problems. Each problem will be graded out of 4 points, indicating your score on that topic. The only possible scores on a topic will be 0, 1, 2, 3, 3.5, and 4. A 3.5 is a temporary score, assigned for example for a small computational error that does not indicate a lack of mastery, and may be rounded up to a 4 per the details given in the section on regrade requests below.

Each Retake is tied to all units up to that point and will have a single problem (with parts) for each topic in that unit. For example Retake ≤B is tied to Unit A and Unit B and will have A1, A2, ..., A5, B1, B2, ..., B5 problems. Each problem will be graded out of 4 points, indicating your score on that topic.

Your final score on a topic will be the maximum of your scores on each assessment. For example if your scores on A3 were [A3 on Midterm A: 1 points] and [A3 on Retake ≤A: 2 points] and [A3 on Retake ≤B: 3 points] and [A3 on Retake ≤C: 2 points] then your final score on A3 would be 3 points, as this was the maximum of your scores. Note that this means, if you ever score 4 points on a topic in an assessment, then you are effectively done with that topic, at least until the final exam.

Midterm and Retake Guidelines. Calculators are not allowed on any Midterms or Retakes. Notes are not allowed on any Midterms or Retakes. You will be provided a ☞ reference sheet however.

Midterm/Retake Absences. Exams must be taken in--person on the specified day. The only exception is for Midterm C in the fall semester, which occurs during the week of Thanksgiving, which you may opt to take on the Friday before Thanksgiving instead, still in--person, in which case you must email your professor to arrange a time.

Otherwise, if you miss a midterm/retake for a valid and documented reason (e.g. sickness with a note from your doctor), then after the final exam has been graded, you may select up to 3 topics that appear on both that midterm/retake and on the final exam and, for each, replace your missing topic score on that midterm/retake with a substitute score from the final exam. Note that certain topics may not appear on the final exam, but you will not know which until the final exam has occurred. If you miss multiple midterms/retakes, the maximum total number of substitute scores from the final exam you can use is 5.

Regrade Requests. If you believe an error has been made in grading, a regrade request can be submitted through Gradescope. Regrade requests may also be used to round up a score of 3.5 up to a 4. To round a 3.5 up to a 4, in your Gradescope regrade reqeust, you must explain your error and how you would correct it. Regrade requests are due about one-and-a-half weeks after each assessment, except for Retake ABC, in which case the regrades will be due a little less than one week after the assessment. If a request to round up a 3.5 is not made by the deadline, your score will be rounded down to a 3.

Contribution to Final Grade. Topic Mastery counts for 60% of your final grade. Therefore each topic contributes 4% to your final grade.

Preparing for Midterms/Retakes. A list of practice problems for each topic is provided on ☞ MyOpenMath. The problems on the exams will be similar to problems that appear in this practice list. If you can rapidly solve the problems from the practice list, without hints, and are comfortable with the core concepts and techniques behind these problems, then you will be well-prepared for the exam. If I have taught the course before, you will also find compilation of past exams and retakes on ☞ MyOpenMath.

Note on Exam Length. The midterms tend to be long, so do not necessarily plan to complete every topic, as you can retry missed topics on a retake. I strongly recommend earning high scores on at least 3 topics. Consider this for example: if for each assessment you are able to obtain 3 new scores of 4/4 then you will have mastered every topic by the end of the semester.

Final Exam

Our sections will have a unique final exam not shared by other instructors.

Date Time Location
Fri Dec 11 2-4pm usual lecture classroom

It is university policy that no student may take this exam early or be allowed to skip it. If you miss the final exam (and were in a position to pass the course prior to taking the final exam) then your only option is to take an "Incomplete" and take the final exam next semester.

Final Exam Guidelines. Calculators are not allowed on the final exam. You will be provided a ☞ formula sheet for the final exam, and are not allowed other notes.

AI Use

You may use generative AI freely at home to assist with your studies.

However, use of generative AI will be prohibited in the classroom, including both lecture and discussion. I believe that these short periods in AI–free zones will encourage you to train neural connections that will help you develop a more flexible understanding of the material and better prepare you for exams.

Discussion Section: Groupwork

Section TA Time Location
39652 Yijie Pan Th 3-3:50pm KAP 163

Format. In discussion section you will work in groups of 3 or 4 to complete an assigned set of problems. Each group will have a randomly selected scribe who will write (on physical paper) and submit work on behalf of the group. Each groupwork will be out of 10 points total: 8 points will be assigned for obtaining correct answers with correct work, while the remaining 2 points will be assigned for presentation and style: is the work presented clearly organized, and is terminology used precisely? (Don't worry, you are not evaluated on the quality of your handwriting, provided your handwriting is, at the very least, legible.) Your TA will be present to assist your group, and can indicate to you what is expected in terms of presentation and style.

Guidelines. It is not possible to work alone, as part of the intention is to train collaboration. All groupwork must be completed and submitted during discussion section. You will submit groupwork through Gradescope, only after your TA has signed off on your submission, and to your TA. It is not possible to earn credit by completing groupwork outside of discussion section, where generative AI use cannot be monitored, as generative AI use is strictly prohibited in the classroom.

Contribution to Final Grade. Discussion groupwork will be worth 10% of the final grade. There will be a groupwork each discussion section, except, in the fall semester, the week of Thanksgiving, and the lowest 2 groupworks are dropped. These drops are intended to account for any reason you may need to miss a discussion section, including sickness or personal emergency.

Lecture: PollEverywhere

Format. During lecture you will asked to respond to roughly 2 multiple choice polls related to the content currently being taught. You wil provide an answer within the specified time limit using the PollEverywhere application, which you may initially access through its tab on ☞ Brightspace. You will receive 75% of the credit merely for an attempt, and the remaining 25% for providing the correct answer.

Guidelines. You must attend lecture in person to complete a poll. As indicated earlier, AI use is not permitted in the classroom. The purpose of the poll is to encourage you to seriously think about the lectured content, and should feel low-stakes due to 75% of the credit being earned merely by answering.

Contribution to Final Grade. Lecture polls will be worth 5% of the final grade. There will be roughly 2 polls each lecture, and the lowest 10 poll scores will be dropped. These drops are intended to account for any reason you may need to miss lecture, including sickness or personal emergency. As indicated, you must attend lecture in person in order to complete the poll.

Lecture: Suggested Problems

Each lecture will be accompanied in the ☞ Daily Schedule by a corresponding set of problems from the ☞ MyOpenMath practice. These suggested problems are not to be submitted, and their solutions will eventually be revealed. However, exam problems will largely be similar to select practice problems, so it would behoove you to study them after each lecture, so you are not overwhelmed in the days leading up to an exam.

Office Hours

These are an essential resource that often go underutilized. We encourage you to attend them to receive help on any aspect of the course. Find them in the ☞ Office Hours tab.

Math Center

The ☞ USC Math Center (KAP 263) is a place to go if you want help with your math classes. It is open during regular business hours and is always stocked with graduate students who can assist you with your mathematics classes.

Academic Integrity

The University of Southern California is foremost a learning community committed to fostering successful scholars and researchers dedicated to the pursuit of knowledge and the transmission of ideas. Academic misconduct is in contrast to the university's mission to educate students through a broad array of first-rank academic, professional, and extracurricular programs and includes any act of dishonesty in the submission of academic work (either in draft or final form).

This course will follow the expectations for academic integrity as stated in the ☞ USC Student Handbook. All students are expected to submit assignments that are original work and prepared specifically for the course/section in this academic term. You may not submit work written by others or "recycle" work prepared for other courses without obtaining written permission from the instructor(s). Students suspected of engaging in academic misconduct will be reported to the Office of Academic Integrity.

Other violations of academic misconduct include, but are not limited to, cheating, plagiarism, fabrication (e.g., falsifying data), knowingly assisting others in acts of academic dishonesty, and any act that gains or is intended to gain an unfair academic advantage.

The impact of academic dishonesty is far-reaching and is considered a serious offense against the university and could result in outcomes such as failure on the assignment, failure in the course, suspension, or even expulsion from the university.

For more information about academic integrity see the ☞ student handbook or the ☞ Office of Academic Integrity's website, and university policies on ☞ Research and Scholarship Misconduct.

Course Content Distribution and Recording Policies

Zoom recordings of lecture will be provided and accessible through the Zoom tab on ☞ Brightspace.

USC has policies that prohibit recording and distribution of any synchronous and asynchronous course content outside of the learning environment.

Recording a university class without the express permission of the instructor and announcement to the class, or unless conducted pursuant to an Office of Student Accessibility Services (OSAS) accommodation. Recording can inhibit free discussion in the future, and thus infringe on the academic freedom of other students as well as the instructor. (☞ Living our Unifying Values: The USC Student Handbook, page 13).

Distribution or use of notes, recordings, exams, or other intellectual property, based on university classes or lectures without the express permission of the instructor for purposes other than individual or group study is not allowed. This includes but is not limited to providing materials for distribution by services publishing course materials. This restriction on unauthorized use also applies to all information, which had been distributed to students or in any way had been displayed for use in relationship to the class, whether obtained in class, via email, on the internet, or via any other media. (☞ Living our Unifying Values: The USC Student Handbook, page 13).

Students and Disability Accommodations

USC welcomes students with disabilities into all of the University’s educational programs. ☞ The Office of Student Accessibility Services (OSAS) is responsible for the determination of appropriate accommodations for students who encounter disability-related barriers. Once a student has completed the OSAS process (registration, initial appointment, and submitted documentation) and accommodations are determined to be reasonable and appropriate, a Letter of Accommodation (LOA) will be available to generate for each course. The LOA must be given to each course instructor by the student and followed up with a discussion. This should be done as early in the semester as possible as accommodations are not retroactive. More information can be found at ☞ osas.usc.edu. You may contact OSAS at (213) 740-0776 or via email at ☞ osasfrontdesk@usc.edu.

Support Systems

Counseling and Mental Health - (213) 740-9355 24/7 on call

Free and confidential mental health treatment for students, including short-term psychotherapy, group counseling, stress fitness workshops, and crisis intervention.

988 Suicide and Crisis Lifeline - 988 for both calls and text messages 24/7 on call

The 988 Suicide and Crisis Lifeline (formerly known as the National Suicide Prevention Lifeline) provides free and confidential emotional support to people in suicidal crisis or emotional distress 24 hours a day, 7 days a week, across the United States. The Lifeline is comprised of a national network of over 200 local crisis centers, combining custom local care and resources with national standards and best practices. The new, shorter phone number makes it easier for people to remember and access mental health crisis services (though the previous 1 (800) 273-8255 number will continue to function indefinitely) and represents a continued commitment to those in crisis.

Relationship and Sexual Violence Prevention Services (RSVP) - (213) 740-9355 (WELL) – 24/7 on call

Free and confidential therapy services, workshops, and training for situations related to gender- and power-based harm (including sexual assault, intimate partner violence, and stalking).

Office for Equity, Equal Opportunity, and Title IX (EEO-TIX) - (213) 740-5086

Information about how to get help or help someone affected by harassment or discrimination, rights of protected classes, reporting options, and additional resources for students, faculty, staff, visitors, and applicants.

Reporting Incidents of Bias or Harassment - (213) 740-5086 or (213) 821-8298

Avenue to report incidents of bias, hate crimes, and microaggressions to the Office for Equity, Equal Opportunity, and Title for appropriate investigation, supportive measures, and response.

The Office of Student Accessibility Services (OSAS) - (213) 740-0776

OSAS ensures equal access for students with disabilities through providing academic accommodations and auxiliary aids in accordance with federal laws and university policy.

USC Campus Support and Intervention - (213) 740-0411

Assists students and families in resolving complex personal, financial, and academic issues adversely affecting their success as a student.

Diversity, Equity and Inclusion - (213) 740-2101

Information on events, programs and training, the Provost’s Diversity and Inclusion Council, Diversity Liaisons for each academic school, chronology, participation, and various resources for students.

USC Emergency - UPC: (213) 740-4321, HSC: (323) 442-1000 – 24/7 on call

Emergency assistance and avenue to report a crime. Latest updates regarding safety, including ways in which instruction will be continued if an officially declared emergency makes travel to campus infeasible.

USC Department of Public Safety - UPC: (213) 740-6000, HSC: (323) 442-1200 – 24/7 on call

Non-emergency assistance or information.

Office of the Ombuds - (213) 821-9556 (UPC) / (323) 442-0382 (HSC)

A safe and confidential place to share your USC-related issues with a University Ombuds who will work with you to explore options or paths to manage your concern.

Occupational Therapy Faculty Practice - (323) 442-2850 or otfp@med.usc.edu

Confidential Lifestyle Redesign services for USC students to support health promoting habits and routines that enhance quality of life and academic performance.